Mischa Barton Makes the Scene

L.A. hotspot Guy’s continues to draw the famous and beautiful into its intimate, cushy environs. On a recent night, Mischa Barton and beau Brandon Davis stopped in, she in a sequined Sass & Bide top and skirt, he in a black jacket. “They sat outside on the patio while Brandon smoked. They seemed relatively happy and affectionate, holding hands on and off until closing time,” a spy tells us. The same night saw Alias’ Michael Vartan at the club, as well as The Fast and the Furious star Jordana Brewster, who had a cast on her leg but still managed to enjoy her friends and her Kir Royales.

Bittersweet Celebration
Two notable invitees missed the recent London launch of the first authorized biography of Princess Diana: her sons, princes William, 22, and Harry, 19. “They had a prior commitment but they sent their best wishes for the event,” says a palace spokeswoman. No official word on where they were, but William was spotted out with pals later the same evening at trendy London nightclub Boujis. Also missing was Diana’s brother, Charles Spencer – though he is quoted in the book, Diana: The Portrait, written with the help of more than 200 interviews with her friends and family (and excerpted in the Sept. 6 issue of PEOPLE). Proceeds from the book will benefit the charities to which Princess Diana was devoted.

Sin City?
Fans of NBC’s drama Las Vegas, rejoice: You have more interesting cameos to look forward to this season (premiering Sept. 13). “Jon Lovitz was there for one. Black Eyed Peas will be there. Alec Baldwin’s coming back,” says the show’s star Josh Duhamel, who is back at work after a relaxing summer vacation. What’d he do? “I got eight weeks off. I went to Costa Rica. I went home and visited family and friends for a few weeks,” he tells us. “Then I, funnily enough, went to Vegas with some friends.” Naturally we wanted to know what he did in Las Vegas. “I can’t tell you that. Are you kidding me? I went with friends,” he says. C’mon, you can tell us…

Caught in the Act
Spotted Recently:
• Ben Affleck, making a surprise visit to the Pacific Palisades, Calif., set of a public service announcement being shot by 17-year-old student Brittany Browder. Alabama native Browder won a competition sponsored by RadioShack in which teens submitted storyboards for PSAs and were judged by a panel including Affleck and his Project Greenlight partners Matt Damon and Chris Moore. Affleck spent about 30 minutes on the set, signed Browder’s storyboard and chatted with her about her family, the South (he has a house in Savannah, Ga.) and the importance of going to college.

• Velvet Revolver frontman Scott Weiland, cuddling with his formerly estranged wife, Mary, at the Kerrang! Awards in London before the band won the prize for best international newcomers. A few tables behind them, Green Day’s Billy Joe Armstrong, his dread-locked wife, Adrienne, and members of his band chatted up friends at The Darkness‘s table.

• Adam Sandler, having breakfast with a female companion at L.A.’s Normandie Cafe.

• Nicole Richie, dining with friends at L.A. eatery Il Sole. “She looked demure in a flowy, cream-colored dress,” says a spy.

• By KWALA MANDEL, SIMON PERRY, DANA MELTZER and MARISA LAUDADIO